Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu

 
Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Planetarium Activities for Student Success            Script

         Strange Planets
                     Planetarium Show

     by Alice Enevoldsen, Alan Gould, Toshi Komatsu, and
                        Steven W. White
           A collaboration of Pacific Science Center
               and the Lawrence Hall of Science
                                                           1
Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Strange Planets
                                                                                                             PASS Classic

Cover photo adaptation
of Milky Way photo by
Carter Roberts.

                                                                                       NASA Kepler spacecraft.
                                                                                   Launched March 6, 2009. Artwork
                                                                                           courtesy NASA.

This material is based upon work supported by the              This work may not be reproduced by mechanical or
National Science Foundation under Grant Number TPE-            electronic means without written permission from the
8751779 and by NASA under Grant NAG2-6067 (NASA                Lawrence Hall of Science, except for pages to be used in
Kepler Mission Education and Public Outreach). There           classroom activities and teacher workshops. For permis-
was also support from the NASA Astrobiology program.           sion to copy portions of this material for other purposes,
Any opinions, findings, and conclusions or recommenda-         please write to: Planetarium Director, Lawrence Hall of
tions expressed in this publication are those of the authors   Science, University of California, Berkeley, CA 94720.
and do not necessarily reflect the views of the National
Science Foundation or NASA.                                    The original edition printing of the Planetarium Activi-
                                                               ties for Student Success series was made possible by a grant
Copyright © 2008, 2009, 2011 by The Regents of                 from Learning Technologies, Inc., manufacturers of the
the University of California, and 2007 by the Pacific          STARLAB Portable Planetarium.
Science Center
                                                               Current PASS publisher (2011) is Sky-Skan Inc. -
                                                               http://www.skyskan.com

                                                                  Planetarium Activities for Student Success
                                                                  For latest information, valuable links, resources
                                                                  relating to the iNTERACT! PASS Classic series,
                                                                  and how to obtain additional copies, visit:
        http://www.lawrencehallofscience.org/                     http://www.lawrencehallofscience.org/pass

2
Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Script

Strange Planets
                         Planetarium Show

                                         Contents
Preface.................................................................................4

Objectives.............................................................................4

Materials...............................................................................5
     Visuals............................................................................................... 8

Recommendations for Using the Script......................12

Variations for Show Length...........................................12

Setup . .................................................................................12

Script . .................................................................................13
     Introduction.................................................................................. 13
     The Spectroscopic Method........................................................ 14
     Stars With Planets........................................................................ 17
     Habitable Zones & Kepler’s Laws................................................ 18
     Transiting Planets......................................................................... 21
     Finding an Earth-like Exoplanet................................................ 24
     Conclusion..................................................................................... 26

About Exoplanets.............................................................28

Acknowledgments...........................................................29

                                                                                                                     3
Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Strange Planets
                                                                                                                 PASS Classic

                           Preface
   “Strange Planets” is a fifty-minute planetarium program about find-        Simple outline:
ing extrasolar planets, focusing especially on the transit method & the
                                                                              5 min		           Intro
Kepler Mission. It was originally designed for a sixth-grade audience.
                                                                              10 min            Spectroscopic Method
  The primary goal of this planetarium show is for the audience to
understand the difficulties of finding extrasolar planets, and to un-         5 min		           Stars with Planets (Pollux, Alrai)
derstand how those difficulties are overcome by modern astronomy              5 min		           Kepler’s Laws & Habitable Zones
techniques.                                                                   10 min            Transiting Planets
   The audience will consider interstellar distances and grapple with the     10 min            Finding an Earth-like Exoplanet
two challenges of finding extrasolar planets—extrasolar planets are very
far away, and are very dim compared to the stars they orbit.                  5 min		           Kepler star field/Conclusion
  We discuss two ways it can be done: through the spectroscopic and
the transit methods.

                                                   Objectives
Students will...
Introduction
Know that hundreds of planets outside our solar system
   have been discovered.
Know that planets outside the solar system are called ex-
   trasolar planets or exoplanets.                                Kepler’s Laws and Habitable Zones

Spectroscopic Method                                              Know that a habitable planet is one that has temperature
                                                                     and conditions for liquid water.
Comprehend the core difficulty in finding extrasolar plan-
  ets: they are too faint to see.                                 Know that planet orbits are oval or elliptical in shape and
Know that many planets have been found by observing               that how quickly a planet orbits its star depends on how
   spectra of starlight.                                          close it is to its star.

Understand that gravity of an extrasolar planet can induced       Transiting Planets
   a star to wobble causing shifting spectral lines (the          Comprehend that a light meter can show brightness
   Doppler shift).                                                  changes.
Know that how much a star wobbles depends on the mass             Know that the transit method of finding extrasolar planets
   of extrasolar planet(s) going around it.                          relies on the fact that a planet periodically blocks star-
Know that how fast a star wobbles is an indicator of how             light, even though we can’t see the planet.
   close it is to its star and hence how high its tempera-        Know that the size of planet is directly related to that
   ture is.                                                          amount of starlight it blocks.
Be shown that because closer, larger planets make their star      Know that how often starlight is blocked is related to
    wobble more they are easier to detect, so it is more likely      how close a planet is to its star and hence the planet
    to discover uninhabitable “Hot Jupiters.”                        temperature and habitability.
Stars with Planets                                                Know some things about NASA’s Kepler Mission.
Be shown the location of a bright star in the sky with a          Finding an Earth-like Exoplanet
   planet.                                                        Analyze a light curve to make conclusions about an ex-
Know that planets can be “strange”, e.g. have a binary star,         trasolar planet’s size and distance from its star (and
   or an orange star.                                                hence, temperature).

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Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Script

                                                                                                    Figure 1. Rainbow Projector
                                Materials
   1. Rainbow projector
       Use a prism or diffraction grating mounted on a light source, such as a flash-
       light, overhead projector, or slide projector. Quality of spectrum is better
       with brighter light source and slit shaped source.
       Easy Alternative: A movie or still image(s) depicting the flashlight/rainbow
       demonstration.
   2. Portable star-planet model
       Make a portable star-planet model that the presenter can carry around to
       demonstrate wobbling motion of a star. The star is a flashlight bulb and the
       planet a large bead or light-weight ball, such as 3/4” polystyrene sphere.                                            Diffraction
       They are mounted on sticks or stiff wire in a way that the model can be                                               grating
       easily spun on a handle (e.g. with wire shaped into a crank) and the star is                                          taped
       off-axis so it will exhibit wobbling motion (Figure 2). See Strange Planets                                           onto
                                                                                                                             flashlight.
       area of PASS website for more ideas on how to build star-planet models
       (http://www.lawrencehallofscience.org/pass).
       Easy Alternative: a movie of a person operating the portable star-planet
       model can be played instead of live presenter carrying a real model
       around.
     Figure 2 Star-planet model—two variations.
       Planet on clip
       (paper clamp)

                             AA Maglite                          The effect is better still if the crank is black or dark colored, with only
                                 (Star)                                           the star (light) and planet balll white.
                                              Optional:
                                Switch        make the                                                            Wire
                                              star-planet                                                                 Polystyrene
                                                                              Mag-lite
                                              distance and                                                                 ball (3/4”)
                                              the amount
                     Wire shaped              of wobble              Ping
                     like a crank             adjustable.            pong
                                              Also have              ball                                      Paper
                                              option of                                                        sleeve
                                              swapping in
                                                                                                                      PVC pipe
                                              two different
                                                                                                                      and fittings
                                              size planets:
                                                                                                                      (1/2”)
                                              large and
                                              small.

3. Orrery (star-multi-planet model) and light sensor for
   real-time light-curves
For the “Transiting Planets” section of the show, you need
a. a fixed star-multi-planet model with (i) two sizes of plan-
                                                                        Easy Alternative for Orrery: movie of
     ets—interchangeable, and (ii) a way to have planets at
                                                                        orrery being used to generate a light
     different distances from the model star.
                                                                        curve (Movies 22a through c; see visuals
b. a light sensor, interface, graphing software, laptop, and            list on page 8).
    videoprojector for projecting real-time light curves on
    the dome.

                                                                                                                                           5
Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Strange Planets
                                                                                                                       PASS Classic

    For the orrery, here are some ideas for how it can be done:                           Figure 3. Fixed star-planet model as orrery.
(a) The portable star-planet model from (2) can be used as a fixed model orrery,
    as long as it can be mounted as target of the light sensor. Use a 15-25 watt
    large spherically-shaped light bulb as a light source instead of the flashlight
                                                                                                              Swing arm lamp
    as a model star. A swing-arm lamp serves well for this purpose (Figures 3
    and 4). To allow planets to be different sizes and orbit radii, a binder clip,
    paper clip, and a planet can serve nicely as adjustable distance (figures 4-5).
(b) Make a multi-planet orrery from LEGO parts (Fig. 7). See the NASA Kepler
    website for instructions on how to build one (http://kepler.nasa.gov/education/
    ModelsandSimulations/LegoOrrery/). Fig. 7 also shows a complete setup of
    LEGO orrery, star (light bulb), sensor, and laptop with light curve visible.
(c) Make a “Walking Orrery” with just one planet (Figure 6). In this variation,
    the star is a flashlight with a transluscent globe fastened on and attached to
    a pole that rests on the floor on a spot marked with a masking tape “X.”
    That’s held by an audience volunteer. A polystyrene planet is put on another
                                                                                                                       Wood base
    pole and held by another volunteer who walks in orbit around the star. The
    light sensor is mounted on another pole at the same height as the star.
   As far as light sensor, our field                                                               Dowel handle inserts
tests were done with a Vernier                                                                     into wood base
light probe and Vernier Logger
                                       Transluscent                          Polystyrene
Lite software. The sensor needs        plastic globe                                                          Figure 4. Planets on clips.
                                                                               planet          Light
to be mounted on a stand at            (Sun)                                                   sensor
about the same height as the                                                                                                Ping pong ball
“star” in the star-planet model.
There are many types of stands
possible. Figure 8 shows one           Light fixture                                    Poles
made of PVC, but it can be                                                              (dowel)            3/4” polystyrene ball
made of metal wire also. Figure
                                        Flashlight
6 shows sensor mounted on a
                                        (Maglite—3 D-cell size)
wood dowel.
   Tinker with the software set-                                                                             Figure 5. Closeup of clip for inter-
tings so that you get a light curve                                                                           changeable planets. Black duct
with easy-to-see characteristics. A                                                                          tape on the clip makes for a more
                                                                                                             secure connection to to the wire.
40-second time period for data
collection is adequate to generate                   Tube to
two curves successively, for side-                   couple PVC
by-side comparison of different                      pole to
size or different distance planets.                  Flashlight
The procedure for acquiring
                                             PVC pole
the side-by-side light curves is             (3/4” x 5’)
described in the script, using the
1-planet model or the Walking
Orrery. Once you get the set-
tings how you like them, save
the file and use that to start up
the software, so that the settings                   Figure 6. The Walking Orrery.
are automatically right for your       All parts easy to obtain. The light fixture (from hardware store)
program.                                  was filed slightly so that the flashlight would screw into it.

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Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Script
                                                                                                       Materials

                                                    Light curve on computer—send to
                                                           large screen display.

                                                                                           7.5 W light bulb.
                 Interface
                    box
                             Light sensor

                                                                                  3-planet LEGO orrery

Figure 7. Real-time light curve setup using LEGO
orrery, light sensor and light mounted on physics                   Figure 8. Light sensor stand made of PVC.
                 poles with clamps.
                                                                                Sight along sensor to aim at “star”
                                                                                light bulb.
                                     Another style
                                     orrery—2 planets.
                                     This is a prototype
                                     for one planned
                                     for commercial
                                     distribution through
                                     Delta Edcuation in
                                     Fall 2011. The crank
                                     is under the base,
                                     below the light. Sensor
                                     stand is attached to
                                     base at left.

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Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Strange Planets
                                                                                                                     PASS Classic
                                                            Visuals
           Media: Still Image / Animation / Movie               Credit/Source
    1.     Kepler launch and dust cover ejection                NASA; Dana Berry
    2.     Still: The first extrasolar planet discovered.       Debivort http://commons.wikimedia.org/wiki/Image:51_Pegasi_b_v3.jpg
    3.     Still: Geoff Marcy                                   Volker Steger
    4.     ALTERNATIVE MOVIE of rainbow demo                    Lawrence Hall of Science: Sindhu Kubendran, A. Gould
    5.     Still: Spectroscopy 1 (star, telescope, diffraction A. Enevoldsen/T. Komatsu
           grating, and absorption spectrum)
    6.     ALTERNATIVE MOVIE of Wobbling Star demo Lawrence Hall of Science: Sindhu Kubendran, A. Gould
    7.     Animation: Spectroscopy 2 (spectral lines shift)     A. Enevoldsen/T. Komatsu
    8.     Still: Jupiter (has a big wobble)                    Cassini Mission - NASA/JPL/University of Arizona http://photo-
                                                                journal.jpl.nasa.gov/catalog/PIA02873
    9.     Still: Mercury (has a fast wobble)                   NASA/MESSENGER Mission - NASA/Johns Hopkins/Carnegie
                                                                http://photojournal.jpl.nasa.gov/catalog/PIA10398
    10.    Still or Animation: Artist’s rendition of a hot NASA/JPL/Cal Tech (still); Dana Berry (animation)
           Jupiter
    11.*   Pot outline for Big Dipper                           G. Steerman, Lawrence Hall of Science
    12.    Bear outline for Big Dipper (optional)               G. Steerman, Lawrence Hall of Science
    13.    Planet with two suns                                 Tim Jones, MacDonald Observatory http://mcdonaldobservatory.
                                                                org/news/releases/2002/1009.html
    14.    Sun-Orange Giant-Red Giant                           http://en.wikipedia.org/wiki/Red_giant
    15.*   Top-view diagram of Solar System, with planets and http://commons.wikimedia.org/wiki/Image:Solar_sys.jpg (use full-
           Sun labeled (optional)                             dome digital version if available)
    16.    Animation: Habitable zone                            NASA Kepler Mission/Dana Berry
    17.    Still: Johannes Kepler                               Museum der Sternwarte Kremsmünster
    18     Still: 1st Law - Orbits are ovals                    A. Gould
    19.    Still: 2nd Law - Equal times/equal areas graphic     http://en.wikipedia.org/wiki/Image:Kepler-second-law.svg
    20.    Animation: 2nd Law - elliptical orbit                http://commons.wikimedia.org/wiki/Image:Classical_Kepler_
                                                                orbit_80frames_e0.6_smaller.gif
    21.    Still: 3rd Law - T2 ∝ r3 chart                       A. Gould, Lawrence Hall of Science
    22.    a-c Movies of Orrery and Live Graphing               Lawrence Hall of Science: M. Nguyen, A. Race, A. Gould
    23.    Still: Kepler spacecraft                             NASA Kepler Mission
    24.    Light Curves Kepler 10b, 11bc, 11de, 11ef, 11        A. Gould/T. Komatsu, Lawrence Hall of Science
    25.    a and b. Size and Distance Lookup Charts             A. Gould, Lawrence Hall of Science
    26.*   a and b. Artist’s depiction of Earth-like planet     Susan Stanley, Lawrence Hall of Science
    27.    a. Still: Kepler’s target area b. Kepler 1st light   NASA Kepler Mission/A. Gould/Carter Roberts
    28.    Animation: Kepler’s Orbit                            NASA, Dana Berry
    29.    a and b. Alternative transit animations              NASA http://www.nasa.gov/mov/159635main_v0634bs.mov or H.
                                                                Deeg and R. Garrido http://www.iac.es/proyecto/tep/transitanim.
                                                                html
    30.    Animation and movie: Diversity of Life               NASA, Dana Berry
    31.    Learn More                                           T. Komatsu, Lawrence Hall of Science
    32.    Credits                                              A. Gould, Lawrence Hall of Science
    * Optional images                       Additional animations and movies can be found at the NASA Kepler website
                                            animations page: http://kepler.nasa.gov/media/animations.html

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Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Handout 1

              Exoplanet Size and
            Distance Lookup Chart*
            Brightness   Planet             Orbit      Orbit
               Drop       Size              Time      Distance
                (%)      (Earth=1)           (days)   (Earth=1AU)
              0.01         1.0                25        1/6
              0.02         1.4                50        1/4
              0.04         2.0               100        0.42
              0.06         2.4               150        1/2
              0.08         2.8               200        2/3
              0.10         3.2               250        0.78
              0.12         3.5               300        7/8
              0.14         3.7               350         .97
              0.3          5.5               400        1.06
              0.5          7.1               450        1.15
              0.7          8.4               500        1.23
              0.9          9.5               550        1.31
              1.0         10.0               600        1.39
                           * For Sun-like stars
                                                                    9
Strange Planets Planetarium Show - by Alice Enevoldsen, Alan Gould, Toshi Komatsu
Handout to take home—front

     Strange Planets
                                             Strange Planets                                                         PASS Classic

      Kepler-10b                                                                                          Period (days)
                                                                                                          ________________
                    0.0%
                         .01                                                                              Distance from Star (AU)
   Brightness
   Change in

                         .02
                         .03
                  -0.05%
                         .04                                                                              ________________
                         .06
                         .07
                         .08
                         .09                                                                              Brightness Change (%)
                  -0.10%
                                    1        2     3     4        5 6 7 8 9 10            11   12   13    ________________
                                                                  Time (in days)                          Planet Size (Earth radii)
                                                                                                          ________________

  Kepler-11b and c                                                                                        Period (days)
                0.0%                                                                                      ________________
                   .01
                   .02
                   .03                                                                                    Distance from Star (AU)
                   .04
               -0.05%    b
                   .06                                                                                    ________________
 Brightness
 Change in

                   .07

                                                              c
                   .08
                   .09
               -0.10%                                                                                     Brightness Change (%)
                   .11
                   .12
                   .13
                   .14
               -0.15%
                                                                                                          ________________
                                                                                                          Planet Size (Earth radii)
                               20    40      60    80    100 120 140 160 180 200   220 240 260 280
                                                             Time (in days)                               ________________

                     0.0%                                                                                 Period (days)
                         .01
 Kepler-11c              .02
                         .03                                                                              1.________ 2.________
                         .04
   and d -0.05.06
               %
                         .07
                                                                                                          Distance from Star (AU)
                         .08
                                                                                                          1.________ 2.________
  Brightness

                         .09
  Change in

                  -0.10%
                         .11
                         .12   d
                   -0.15%
                         .13
                         .14                                                                              Brightness Change (%)
                         .16
                         .17                                                                              1.________ 2.________
                         .18
                         .19             e
                   -0.20%                                                                                 Planet Size (Earth radii)
                                    20       40    60    80   100 120 140 160 180 200   220 240 260 280
                                                                   Time (in days)                         1.________ 2.________

  Kepler-11e and f                                                                                        Period (days)
                0.0%                                                                                      1.________ 2.________
                   .01
                   .02
                   .03                                                                                    Distance from Star (AU)
                   .04
              -0.05%
                   .06
                                                              f                                           1.________ 2.________
 Brightness
 Change in

                   .07
                   .08
                   .09
               -0.10%
                   .11
                                                                                                          Brightness Change (%)
                                                                    g
                   .12
                   .13                                                                                    1.________ 2.________
                               20       40    60    80   100 120 140 160 180 200    220 240 260 280
                                                                                                          Planet Size (Earth radii)
                                                              Time (in days)
                                                                                                          1.________ 2.________
      10
                                                                                © 2008 by The Regents of the University of California
Orbit Time
                                 25     50     75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500 525 550 575 600
           (in days)
     Distance from Star
                        0.17 0.27 0.35 0.42 0.49 0.55 0.61 0.67 0.72 0.78 0.83 0.88 0.93 0.97 1.02 1.06 1.11 1.15 1.19 1.23 1.27 1.31 1.35 1.39
                                                                                                                                                                                              Handout to take home—back

           (in AU)

     Brightness Change
                       0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00
            (i%)
        Planet Size
                           1.0    1.4    1.7    2.0   2.2   2.4   2.6   2.8   3.0   3.2   3.3   3.5   3.6   3.7   3.9   4.5   5.5     6.3    7.1    7.7    8.4   8.9    9.5 10.0
        (in Earth-radii)

     1 AU = average distance from Earth to the Sun
     For a Sun-like star, the Habitable Zone is 0.95-1.37 AU.

     Are any of the planets nearly Earth-size and
     in the habitable zone of its star (near 1 AU)?
     Which one(s)? __________

     Links for more information:

      Kepler Mission Home Page:
      http://kepler.nasa.gov/
                                                                                                                                    Hypothetical Icy Planet.
      Kepler Star Wheel:                                    California & Carnegie Planet Search                                                           Artwork by Susan Stanley
      http://kepler.nasa.gov/ed/starwheel/                  http://exoplanets.org/

      Make a LEGO® Orrery:                                  The Extrasolar Planets Encyclopaedia
      http://kepler.nasa.gov/ed/sim/lego.html               http://exoplanet.eu/

      PlanetQuest: Exoplanet Exploration

11
                                                                                                                                                                                     Script

                                                            Top 10 Most Intriguing Extrasolar Planets
      http://planetquest.jpl.nasa.gov/                      http://www.space.com/scienceastronomy/extrasolar_planets.html

                                                                                                                        © 2009 by The Regents of the University of California
Strange Planets
                                                                                                         PASS Classic

                                    Setup
1. Set sky to a time when both Cygnus & Gemini are visible, e.g. May 25, 22:00,
    local time
2. Cue up images & videos
3. Rainbow maker ready (diffraction grating & flashlight)
4. Spinning star-planet models ready. Set up orrery.
5. Set up Vernier Light sensor, interface, laptop with graphing software, and video-
    projector
6. Optional Handouts ready: Strange Planets take-home handout and
     Exoplanet Size and Orbit Size Lookup Chart (pp. 9–11)

        Recommendations for
          Using the Script
  We don’t expect the script which follows to be memorized (as an
actor might memorize a part) but to be used as a guide in learning,
                                                                                 Variations for
rehearsing, and improving presentations. We recommend that you                    Show Length
read the script once or twice, then work with it in the planetarium,       The show is intended to be 50 minutes long,
practicing the projector controls, slides, special effects, and music.     including all sections, except for the detailed
You should be able to imagine yourself presenting information,             treatment of Kepler’s Laws. However, many
asking questions, and responding to participants. For your first few       variations and adaptations are possible.
presentations, you can have the script on hand, using major headings
as reminders of what to do next.                                                                          Length of show
  The script is organized in blocks or sections. The purpose of these                                        in minutes
separations is only to help you learn and remember what comes next.                                          50 40 30
Once you have begun a section, the slides or special effects and your      Introduction__________________ 4 4 4
own train of thought will keep you on track. When beginning a new          The Spectroscopic Method_ _____ 4 4
section, make the transition logically and smoothly.                       Stars With Planets_____________ 4 4 4
   Directions for the instructor are printed in italics in the side col-   Habitable Zones, Kepler’s Laws___ 4
umn, the instructor’s narrative is printed in regular type, and direc-     Transiting Planets______________ 4 4 4
tions and questions to which the audience is expected to respond are
                                                                           Finding an Earth-like Exoplanet__ 4       4
printed in bold italics. There is no point in memorizing narration
word-for-word since what you need to say will depend upon the              Conclusion___________________ 4 4 4
participants. The language you use and the number and kinds of
questions you ask will depend on how old the participants are, how
willing they are to respond, and how easily they seem to understand
what is going on.
   We believe that the most important elements of the program are the
questions and the activities since these involve the audience in active
learning. If you must shorten your presentation, we recommend that
you borrow time from the narration.

12
Script

                                                       Script
                                                                              Dim house lights and bring out stars.
                                                                              Fade music.

                                                  Introduction
Hello, and welcome to the ________ Planetarium. Our program is
called Strange Planets. But of course, strange is in the eye of the be-
holder. Any planet might seem strange.
We have eight planets in the Solar System, all very different and each
strange in its own way. We know at least one has life—Earth, a strange
planet, partly because of all the strange people on it.
Are there places other than Earth that could have life?
                                                                              [Accept answers and encourage discus-
                                                                              sion with other questions.]
We use the word habitable for a place that can support life.
People have long wondered…are we alone? [Point towards starry
sky.] If there are a lot of other planets circling stars out there beyond
the Solar System, we could greatly expand the possibilities for finding
habitable places.
There HAVE been planets discovered around other stars. They are
called extra-solar planets or exoplanets for short.
    Do you know how many exoplanets have been discovered?
[Accept answers. As of May 2011, “over 530” is correct. See The Ex-
trasolar Planets Encyclopedia at http://exoplanet.eu/ or the New Worlds
Atlas at the PlanetQuest website — http://planetquest.jpl.nasa.gov/]           If possible, show live or recent screenshot
    Optional, if correct answer is not given:                                  of the PlanetQuest New Worlds Atlas page
                                                                               that has up-to-date exoplanet count:
    Raise your hand if you think there are less than 50 planets                http://planetquest.jpl.nasa.gov/
    discovered? Less than 100? Less than 400?
We’ve discovered over 530 [use current planet count] planets outside of our
solar system. Most of the extrasolar planets discovered have been quite
large—the size of Jupiter or even bigger.
                            VISUAL 1: Kepler Launch. Movie of Kepler
                            spacecraft launch (2009 March 6) and
                            animation of dust cover ejection (2009 April
                            7). Alternatively, show some combination of
                            the launch, deployment, and/or dust cover
                            ejection in videos sp01b–d. Add music for
                            animations. l
NASA’s Kepler Mission, launched in March of 2009. When its dust
cover was ejected, it started collecting data on the brightness of 100,000
stars. It is designed to detect evidence of planets that are roughly the
size of the Earth and suitable for life!

                                                                                                                       13
Strange Planets
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                                   The Spectroscopic Method
Finding extrasolar planets is really tough.
     Why do you think finding exoplanets is so hard?
[Extrasolar planets are extremely dim, very close to their stars, and so
far away that the star’s glare ruins our chances of seeing the planets.]
For decades, astronomers had suspected there were extrasolar planets
out there, but there was never any proof until 1995.
                           VISUAL 2. Still image of 51 Pegasi, the
                           first extrasolar planet discovered. Add
                           music. l
Here we see an artist’s concept of the first confirmed extrasolar planet
ever discovered, orbiting around a star called 51 Pegasi. It’s an artists
concept because it’s impossible for us to actually see the planet, even
with out most powerful telescopes.
To find such planets, we must resort to clever and ingenious meth-
ods. Most exoplanets, so far, have been detected by the Spectroscopic
Method.

                           VISUAL 3. Still image of Geoff Marcy.
                           Fade music. l
This is the world’s pre-eminent planet-finder—UC Berkeley astronomer,
Geoff Marcy. He and his team pioneered a planet-finding technique
called the spectroscopic method. Here is how it works.
                                                                            Switch on the flashlight & diffraction grat-
                                                                            ing and beam a rainbow on the audience.
                                                                            Turn a circle and sweep the rainbow over
                                                                            everybody and across the dome.
                                                                            OR ALTERNATIVELY...show
                           VISUAL 4. Rainbow movie (or still image)
                           alternative to live demo of flashlight with
                           diffraction grating. Use music. l

There is something called a diffraction grating on this flashlight. It
works kind of like a prism.
     What happens when light passes through a prism?
         [Take any answers.]
The rainbow you see is called a spectrum. You can see all the colors
from the flashlight separately—each one all stretched out. [Fade
music.]
                           VISUAL 5. (still) Spectroscopy 1,
                           showing a star, a diffraction grating,
                           and an absorption spectrum of the star
                           with lines. l

14
Script

We look at a star with a telescope that has a diffraction grating; the
starlight stretches out into a rainbow spectrum. You can see dark lines
in the rainbow spectrum where the star is actually missing those colors
because different chemicals, like hydrogen and helium and sodium,
swallow up those colors. Now here’s the key to planet-finding using
the spectrum….
                                                                           Turn on the “star” on the wobbling star/
                                                                           planet model and walk around without
                                                                           spinning the star. The star should move
                                                                           very smoothly. Add music.
Here we have a star with no planet orbiting it.
    Does it seem to you to be moving steadily? [Yes.]
Now let’s add a planet orbiting the star.
                                                                           Start spinning the planet around the star.
                                                                           The star should appear to wobble.
                           ALTERNATIVE:
                           VISUAL 6. Wobbling star movie can be played
                           as alternative to showing the wobbling star
                           model live. Add music. l
    What’s unusual about how is “star” is moving now?
     [It appears to wobble.]
    What do you think is causing the star to wobble?
     _[The planet’s gravity is tugging on its star.]
The planet’s gravity makes the star move back and forth as the planet
orbits, but since planets are so much smaller than stars, the wobble is
a teeny-tiny wobble.
                           VISUAL 7. (animation) Spectroscopy
                           2, where the star is wobbling and the
                           absorption lines wobble with it. Use
                           music. l
If the star is wobbling towards us and away from us, it affects the
rainbow/spectrum of the starlight. When the star moves toward us, all
the dark (absorption) lines in the spectrum shift slightly over toward
the blue side of the rainbow spectrum. That’s called a blue shift. When
the star is moving away from us, all the dark lines shift the other way,
toward the red side.
    Guess what that’s called? [Red shift. ]
                             OPTIONAL
                                                                           Optional: Have half the audience clap
                                                                           when the animation shows blue shift and
                                                                           the other half of the audience clap when
                                                                           the animation shows red shift.
The cause of red shift and blue shift is a lot like what happens when
a sound, such as a train or race car, slides down in pitch as it goes by
you.
                                                                           Play audio sample of a Doppler shift.

                                                                                                                   15
Strange Planets
                                                                              PASS Classic
When studying these wobbles, we look for two features—the size of
the wobble, and the speed of the wobble.
     What might cause a really big wobble?
[A big massive planet, ...or planet very close to the star.]
     What might cause a really small wobble?
[A small planet, ...or planet far from the star.] It’s the gravity of
the planet that makes the star wobble and the force of gravity is stron-
ger if the planet is more massive or closer to the star.
     How about the speed of the wobble?
     What might cause a really slow wobble?
[A slow wobble means the planet is orbiting slowly.] The further
the planet is from its star, the slower the wobble.
     What might cause a fast wobble?
[A fast wobble means the planet orbits quickly around its star,
and hence is closer to its star.]
     If an alien astronomer were watching the spectrum of our Sun,
     which planet do you think would create the biggest wobble?
                            VISUAL 8. (still) Jupiter. l
  [The biggest planet, Jupiter. If necessary, prompt by asking
what the biggest planet is. Mercury is the closest planet, but
not very big at all. Jupiter’s gravity affects the Sun a lot more
than Jupiter’s even though it’s much farther away.]
     Which planet would make the fastest wobble?
[Mercury. If necessary, prompt by asking what the closest
planet to the Sun is. The amount of wobble would be tiny.]
                            VISUAL 9. (still) Mercury (has fast wobble). l
Actually, Mercury would make a fast wobble, but also a very small
wobble since it’s not very massive. Most of the extrasolar planets we
know of have been found by studying these spectrum wobbles, and
they have been quite large—many bigger than Jupiter. Not only that,
most of the planet discoveries have been ones that orbit close to their
stars. That’s because large wobbles and fast wobbles are much easier to
find than small, slow wobbles.
     If a planet is orbiting close to its star, what would that do to
     the planet’s temperature? [It would be hot.]
Those large planets with close in orbits we often call “hot Jupiters.”
                            VISUAL 10 (still or animation) Artist’s
                            rendition of a hot Jupiter. l
This is a picture of what a hot-Jupiter extrasolar planet might look
like. Of course, we’ve never seen one directly. It might look like Jupiter,
but being so hot, it could be a strange planet indeed. In fact, people
thought Jupiter-size planets so close to at star would be impossible in
light of theories of solar system formation at the time. Theories were
shattered.

16
Script

                                            Stars With Planets
In our planetarium sky, there are a couple of stars that have giant-size
planets orbiting them, but with Mars-like orbits—farther out from
their stars than Earth is from the Sun. They are not hot Jupiters. Are
they strange planets?
You can see one of those stars year-round in the constellation of
Cepheus. To find Cepheus, let’s start with a more familiar group of
stars.
    Ha you ever seen the Big Dipper before? Can anyone point it
    out for us? [Take any answers.]
It has seven bright stars, shaped like a pot with a long curving handle.
                            VISUAL 11 Pot outline on the dipper stars. l
There it is! Some people think of it as part of a giant ferocious bear.

                            VISUAL 12 Bear outline (optional). l
The Big Dipper can be used to point to the North Star. See these two
stars? [Indicate the Pointer Stars.] They’re called the Pointer Stars
because they point to the North Star, also called Polaris. It’s always
in exactly the same spot in the north. If you can find the North Star,
you’ll never get lost.
                                                                               Follow the pointer stars to Polaris, and
                                                                               indicate.
Here’s the North Star! And if you keep going a little farther [continue
to Cepheus] you’ll find this bright star.
                                                                               Point to Gamma Cephei (Alrai).
That star is in the constellation Cepheus, the King. The star called
Gamma Cephei, which means “third-brightest-in-Cepheus.” Its Arabic
name is Alrai (a.k.a. Errai, or Er Rai). It’s is 45 light-years away, and is
a binary star system: two stars revolving around one another every 50
years or so. Imagine having 2 suns in your sky! A strange planet indeed.

                            VISUAL 13. Planet with two suns.
                            Add music. l

                                                                               Optional: Hand out Uncle Al’s Kepler Star
                                                                               Wheels (master on Kepler website), have
                                                                               the audience set them for May 25 at 10
                                                                               pm, and find Alrai (Gamma Cephei) on
                                                                               the star wheel. Explain how to adjust the
                                                                               Star Wheel, and let them know that you’ll
                                                                               be telling them how to get their own copy
                                                                               to make from a web page that you’ll give
                                                                               them.

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Strange Planets
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The planet is bigger than Jupiter, about 1.5 times Jupiter’s mass, and is
going around the larger star of the binary system. It’s year is 2½ Earth
years, and a tad bit farther from it’s sun than our Mars is from our Sun.
Another star with a planet can be found in this very famous winter
constellation, Gemini.
                                                                              Point out Gemini, with outline.
                                                                              Fade music.
The brightest star in Gemini is this one, Pollux [point to and show
label]. It’s 34 light-years away, and the brightest star known to have
an extrasolar planet. The planet is even bigger than Alrai’s—more than
twice the mass of Jupiter—and orbits in about 590 days, which is
similar to Mars in our solar system. You can see this star from about
October (around midnight) through June (just after sunset). Is this a
strange planet? Well, Pollux is an orange giant star, evolving into its red
giant stage. So yes, you might call this a strange planet with an orange
giant sun. Once Pollux is fully evolved into a red giant, it may have
grown to size so big that it will engulf this planet!
                            VISUAL 14. Sun, Orange Giant, Red
                            Giant size comparison. l

                                                                              Optional: Find Pollux on Uncle Al’s
                                                                              Kepler Star Wheels.

                                                                              Optional: Show exoplanets (fulldome
                                                                              digital systems) and explain that it shows
                                                                              a some of the over 300 planets discov-
                                                                              ered to date.

                            Habitable Zones & Kepler’s Laws
We’re especially interested in planets that might be good homes for
living things.
                            VISUAL 15. (still) Top-view diagram of
                            Solar System. l

                                                                              Optional: Show fulldome digital view
                                                                              from above Solar System, with planets
                                                                              labeled/marked & orbits on.
     Why don’t we expect to find life on Jupiter or Mercury?
[Jupiter is made of mostly gas, with very high pressures, and
we don’t even know if it has a solid surface, though it’s thought
to have a rocky core. Mercury is simply too hot—water would
vaporize rapidly. It’s also so small, it’s gravity is not strong
enough to hold onto an atmosphere.]

18
Script

Hot Jupiters are gas giants that are too hot, unlikely to have life. Ju-
piter’s moon, Europa, is another story altogether. It has liquid water
ocean below a crust of ice.
So what about finding planets more like Earth?
    What are the conditions that make Earth good for life?
[Take any answers, but focus towards the idea that Earth is
not too hot, not too cold, not too big and not too small.]
The key is water. And not just any kind of water.
    What would happen to water on Mercury where the temperature
    is over 600 degrees? [It boils.]
    What happens to water in the outer parts of the solar system
    where it’s REALLY cold? [It freezes.]
Water in the form of ice or steam is not what living things are made of.
Life needs LIQUID water. So, like Goldilocks and the Three Bears,
we need a planet that’s not too hot, not too cold, but juuuust right.
So we are really keen on finding a planet has the right size orbit
that keeps the planet not too far and not too close to its star. This
is sometimes called the goldilocks zone, but it’s more formally called
the habitable zone.
                           VISUAL 16. (animation) Habitable
                           Zone. l
Size is also important.
    Very small planets with low gravity would not be suitable for
    life? Why do you think that is?
[Not enough gravity to hold an atmosphere.]
And we already talked about why a big planet is not suitable for life: gas
giants have crushing atmospheric pressures. So just as with temperature,
there is a magic “Goldilocks zone” of size: not too big and not too
small, but juuuust right—about Earth-size or thereabouts.
...Which brings us back to the NASA Kepler mission. It’s designed
to find planets and for each discovered planet, determine its size and
distance from its star. It’s main mission is to find Earth-size planets in the
habitable zone of stars.
                           VISUAL 17. (still) Johannes Kepler. l

                                                                             The following section on Kepler’s Laws
                                                                             may be omitted for most audiences.

                                                                                                                  19
Strange Planets
                                                                                                          PASS Classic

Kepler’s name honors a mathematician and astronomer, Johannes
Kepler, who, 400 years ago was an assistant to Tycho Brahe—the
greatest observational astronomer of his time. Brahe over decades
had made detailed astronomical observations. Kepler used Brahe’s
astronomical tables to formulate three laws of planetary motion that, for
the first time, could predict the positions of planets with great accuracy.

                        Kepler’s First Law
     Do you know what shape orbits of planets have? [Ellipses,
     or ovals.]
                            VISUAL 18. (still) Orbits are ovals
                            graphic. l

                                                                              Optional: Keep showing fulldome digital
                                                                              top view of solar system.
That’s Kepler’s First Law of Planetary Motion—that planets move
in elliptical orbits. Most planets have nearly circular orbits, but not
perfectly circular.
     What keeps the planets in their orbits? [Gravity.]
Right. Kepler didn’t know about gravity, but he did notice a pattern to
how fast a planet moves at different places in its orbit.

                     Kepler’s Second Law
                            VISUAL 19. (still) Equal times/equal
                            areas graphic. l
He described an imaginary a line drawn from a planet to its star. The
area swept by that line when it’s closer to the star looks different from
the area swept by the line when the planet’s farther from the star.
     Which area looks larger, the one when the planet is closer or
     the one when the planet is farther from its star?
Trick question. Actually, they are exactly the same size. And that’s
Kepler’s second law: a planet sweeps out equal areas in equal times. A
simpler way to think of it is that a planet moves faster when it is close
to the Sun and slower when it is further from the Sun.
                            VISUAL 20. (animation) Equal times/
                            equal areas graphic. l
                            Music—music of the spheres....

20
Script

    And what’s causing that to happen—the planet moving faster
    when it’s closer to the Sun? [Gravity.]
Remember, Kepler did not know about gravity, so he did not know
why his second law works. In fact, no one had an explanation until
Isaac Newton came along with his law of universal gravitation some
70 years later.

                      Kepler’s Third Law
Kepler’s third law is the most important one for the NASA Kepler
mission. Johannes Kepler was a firm believer that the physical properties
of the Universe could be described purely by mathematics. So, looking
for more patterns in the data, he discovered the mathematical
relationship between distance a planet is from its star and the time it
takes to orbit: the square of the orbit time is proporational to the cube
of the orbit distance.
                           VISUAL 21. (still) Graph of Kepler’s
                           3rd Law (T2 ∝ d3). Don’t mention log
                           scales unless someone asks. l
This graph shows Kepler’s 3rd law.
    Optional: Explain the graph. The y-axis is planet orbit time and the
    x-axis is planet distance “Astronomical Units” or AUs for short. You
    can see on the graph Earth’s orbit time is 1 year and distance is one
    AU—in fact that’s the definition of an AU: the average distance from
    the Earth to the Sun. Saturn’s at about 10 AU and takes about 30
    Earth years to orbit the Sun.
Kepler’s 3rd Law lets us calculate the distance of a planet from its star
if we can find the time it takes to orbit. And the distance, as you now
know, is critical to whether or not the planet is in the habitable zone!

                                          Transiting Planets
Using another very clever technique, we can not only discover extrasolar
planets, but determine fairly accurately how big they are and, armed
with Kepler’s Third Law, we can find out how far they are from the star.
                           If you do not have an orrery with light sensor, and
                           the system for projecting light curve graphs in
                           real time, you may use the Orrery and Live-Graph
                           movies.
                                            However, using the real live
                                             orrery/light curve set-up is
                                             much more fun....
                                               nVISUAL 22a. Orrery movie. Point out light
                                               sensor, model star (light) and planets. Explain
                                               that the sensor will feed star brightness data to
                                               a computer and show us a graph of brightness
                                               changes.
                                               VISUALS 22b and c. Movie of the orrery in action synchronized
                                               with the live light curve graph. You can show these side by side or
                                               one above the other, in lieu of the a full-blown sumulation setup.

                                                                                                               21
Strange Planets
                                                                                                           PASS Classic

For live presentation, use either hand-crank demon-
                                                                  Light
stration orrery (LEGO model or equivalent, shown
                                                                 Sensor
right) or the “Walking Orrery” (below).

                                                    Light
                                                   Sensor

                                                                             On the orrery make sure the light sensor
                                                                             is aimed at the star-bulb. Switch on the
                                                                             video projector and wake up the laptop,
                                                                             to feed data from the light sensor to the
                                                                             projector, to show Brightness vs. Time
                                                                             graph on the dome.
                                                                             Caution the audience that you are about
                                                                             to turn on a model star, then turn on the
                                                                             model star, but do not spin it yet.
This is a light sensor that measures the brightness of the star. We can
think of this as a model of the NASA Kepler spacecraft and its light
sensing camera. [Optional: It’s also called a photometer because it
measures amount of photons of light.]
                                                                             Vary the display in an obvious way—by
                                                                             putting your fingers or hand between the
                                                                             sensor and the light.
Look! That picture shows the brightness of the star! It’s a graph of light
brightness—called a light curve. You can even tell how long my hand is
blocking the light without even being able to see my hand. Just look
at the light curve....
                                                                             Optional: Have audience volunteers
                                                                             block the light with their hands.
                                                                             Let the graph stabilize so the audience
                                                                             can see the flat line that represents the
                                                                             normal star’s brightness, as detected by
                                                                             our “telescope” sensor. Then point out
                                                                             the Orrery.
This is a model star with extrasolar planets we are trying to find.

22
Script

   Light                                                                         Run the orrery by having a volunteer
                                                                                 holding the panet walk around a volun-
   curve
                                                                                 teer holding the star (for Walking Orrery)
    from
                                                                                 or by turning the crank on the orrery so
2-planet                                                                         the planet(s) periodically block the light
  orrery.                                                                        entering the sensor, making a light-curve
                                                                                 graph. If using volunteer instruct them to
                                                                                 crank gently and steadily. If the volunteer
                                                                                 is somewhat erratic, you can comment
                                                                                 that it looks like our solar system machin-
                                                                                 ery is “only human.”
    What happens when this extrasolar planet passes between the
    star and our photometer? [There is a dip in the graph.]
The extrasolar planet is blocking the light from the star, and our sensor
detects it! What a great way to find extrasolar planets! It’s like an eclipse.
Astronomers call it a “transit,” which means “going across.” Looking for
stars that are having their light blocked as a planet goes across is called
the “Transit Method” of finding extrasolar planets.
One limitation of the Transit Method is that it only works if the extra-
solar planet and its star are tipped just the right way.
    What if the extrasolar planet orbited the star at an angle that
    was not lined up with our sensor? [No transit could be
    detected.]
Let’s see what we can tell from this light curve graph.
                                                                                 Have a volunteer crank the orrery or for
                                                                                 the Walking Orrery, have two volunteers:
                                                                                 one to hold the star and the other to walk
                                                                                 around it with the planet.
    How can you tell from the light curve if a planet is big or small?
_[Big planets make deeper dips in brightness.]
We can also measure how often light is blocked—that means how much                      If you have an orrery with only 1 planet
                                                                                        (the Portable Star-Planet model or the
time passes from here to here on the graph [point out the distance                      Walking Orrery), you can still analyze
between dips on the projected graph]. We saw this before, too! That’s                   light curves as follows: Have an audi-
the period.                                                                             ence member volunteer turn the crank
                                                                                        (or walk around, in the case of the Walk-
    How can you tell from the light curve if the planet is close to                     ing Orrery) but after 15 or 20 seconds,
    or far away from its star?                                                          ask them to stop so you can quickly put
                                                                                        on (or hand them) a different size planet.
    [Farther out planets make dips that are more widely                                 Ask them to continue cranking (or walk-
    spaced.]                                                                            ing) at as steady a speed as they can.
                                                                                        In this way, you will generate two “half”
If the dips on the light curve graph are close together—then the planet                 light curves, side by side. In many ways,
is orbiting the star really fast, and it must be really close to the star.              this is even easier for people to analyze
That means it is a hot planet.                                                          than the light curve with two planets
                                                                                        going simultaneously.
Look how close the dips are in that light curve graph!

                                                                                                                            23
Strange Planets
                                                                                                                  PASS Classic
                                                                               To compare the effect of orbit distance, again have
[Point to most closely spaced dips]                                            a volunteer crank the Star-Planet model (or walk
That’s a close, hot planet!                                                    around), but this time, explain that instead of chang-
                                                                               ing planet size, you are going to change how far
[Point to most widely spaced dips]                                             the planet is from the star, which affects how fast
Then the planet would have to be far away from the star, and that              it moves. Have the volunteer start by cranking (or
                                                                               walking) fairly fast. Start the data collecting and, after
means it is a colder planet. Look how far apart the dips are on that           15-20 seconds, have the volunteer stop, quickly move
light curve graph! That planet is really creeping—must be far from its         the planet farther out on the arm, and instruct the
star. Brrr! That’s a cold planet!                                              volunteer continue cranking but slower. In the case
                                                                               of the Walking Orrery, just have the volunteer walk
Since big planets block a lot of light and small planets only block a          more slowly in the second part of data collecting.
little bit of light, big planets are easier to find than small planets! Just
like with the spectra of star wobbles. Big hot Jupiters are the easiest
to find.
                              VISUAL 23. Still image
                              of Kepler spacecraft. l
The Kepler instrument uses a light sensor like the one we’ve been us-
ing today, except that it’s huge, with nearly 100 million pixels, and it’s
in a big telescope to collect lots of light. How many pixels does your
digital camera have? 5 megapixels? 8 megapixels? I bet it’s not 100
megapixels, like the Kepler spacecraft camera!
The transit method of planet finding is second only to the spectroscopic
method in terms of numbers of planets discovered so far, but the Kepler
Mission could change all that. In February of 2011, the Kepler team released data
containing 1,235 planet candidates. The planet candidates are not all
confirmed planets, but many of them are very likely real planets.

        Finding an Earth-like Exoplanet
So if we will be getting all this data from the Kepler mission, how will
we know if we do find an Earth-like planet in the habitable zone? Let’s
imagine we are the planet finders and have look at some data.
                              VISUAL 24. Light Curve Kepler-10b. l
Here is light curve data from one of the Kepler stars that has a discov-
ered planet named Kepler-10b. We can determine how big the planet
is from how deep the dips in brightness are.
     On the Kepler 10b graph, how deep is the dip, in % brightness
     drop?
     [Almost .02%.]
                              VISUAL 25a. Still image of Planet Size Lookup
                              Chart. l
Look at the Brightness Change vs Planet Size Lookup Chart.
     How big is a planet with .02% brightness change?
     [About 1.4 times Earth size]
You can also determine how far the planet is from it’s star by measuring
how widely-spaced the brightness drops are, to find the planet’s orbit
time (period).

24
Script

    On the Kepler 10b graph, what is the orbit time? [About 0.8
    days.]
                          VISUAL 25b. Still image of Orbit Distance
                          Lookup Chart. l
Now look on the Orbit Time vs Orbit Distance Lookup Chart.
    How far out is a planet with a 0.8 day period?
    [Less than 0.02 AU or about 6 times the Earth-Moon
    distance.]
    Is that an Earth size planet? [Close.] Is it in the habitable zone?
    [No.]

Let’s look at Light Curve for the star Kepler-11.
                          VISUALS 25. Light Curves for
                          Kepler 11a, b, c, d, e, f, shown in
                          3 graphs, 1 pair in
                          each graph. l
Here you should be able to see 2 planets in each of the light
curve graphs. Let’s pick one planet to focus on, say Kepler-11c.
    How deep is the dip, in % brightness drop for Kepler-11c?
    [0.1 or one tenth of 1%]
    From the Planet Size Lookup Chart, how big is a planet
    with 0.1% brightness change?
    [About 3.2 times Earth’s size]
    What is the Orbit Time for Kepler-11c?
    [About 13 days.]
Now look on the Orbit Distance Lookup Chart.
How far out is a planet with a 13 day period?
    [About 0.06 AU or about 1/16 the distance from Earth
    to the Sun.]
                                                                          Optional Technique (takes longer): After
    Is that an Earth size planet? Is it in the habitable zone? [No.       analyzing light curve for Kepler-10b as a
    It’s closer to the size of Uranus and way too close to the            whole group, have “small groups” analyze the
    Sun.]                                                                 rest of the light curves, Kepler-11a through
                                                                          f. Give out the Strange Planets take-home
    Optional:Pick one or more other planets of Kepler-11 and              handout to each group to find Size and
    do similar analyses to determine planet size and size of              Distance for each of the exoplanets from the
                                                                          light curves. Remind them they are looking
    orbit.                                                                for an Earth-size planet that is in the habit-
                                                                          able zone of its star. If a group finishes it’s
                                                                          assigned star, they can go ahead and pick
                                                                          another star to work on.
                                                                          Turn on “planet-finding music.”
                                                                          After all have found results on their assigned
                                                                          star, have a discussion with the group as a
                                                                          whole about whether any of the planet(s)
                                                                          are Earth-like and habitable, and how they
                                                                          know that.

                                                                                                                       25
Strange Planets
                                                                                                            PASS Classic
Optional: Show combined light curve for Kepler-11a, b, c, d, e, f, in color coded version
and/or simple black and white with no labels. This shows an inkling of complexity of
what the Kepler light curve analysts are dealing with.

                                  VISUALS 26a and b. Optional: Artist’s
                                  conception of Earth-size planet. l
                                  What does it look like—this potentially
                                  habitable planet we found? What is its
                                  surface like? Does it actually have life?
                                  If it does, what is that life like?
                                  Isn’t it amazing that just by studying a
                                  light curve graph of a star’s brightness
over time, we can learn such a tremendous amount? We can find out
a planet’s size, how long its year is, how far it is from its star, and even
the prospects for it supporting life!

                                                    Conclusion
                                                                               Fulldome digital: Turn on all exoplanets.
                                                                               Music.
We are finding new extrasolar planets all the time. But the goal is to
find these habitable, Earth-like planets.
                                    VISUAL 27. (still) Kepler’s target area.
                                    Three versions of this are available.
                                    One has the star field with the CCD
                                    pattern superimposed. Another is
                                    just the CCD pattern that you can
                                    position over the actual stars in your
                                    planetarium—especially suitable for
                                    digital star projectors. The third is first
                                    light image from the Kepler spacecraft,
                                    produced in April 2009.
                                   The NASA Kepler mission is specifi-
cally designed to survey our region of the Milky Way galaxy, to discover
hundreds of planets. Kepler is staring at a this section of the sky, that
you see here near the constellation Cygnus (the Swan), staring for three
and a half years, never blinking, and surveying about 150,000 stars
simultaneously.

26
Script

                            VISUAL 28. Animation of Kepler’s orbit
                            around the Sun. l
Kepler is following (trail) Earth in its orbit around the Sun. Every three
months, Kepler executes a 90° roll to keep its solar panels pointed
towards the Sun and at the same time keep its exquisitely sensitive
photometer (light meter) aimed at those 150,000 stars.
                            VISUALS 29a and/or b. (animations)
                            Transit. Animation (a) has no light
                            curve graph. Animation (b) shows
                            light curve along with transiting planet
                            animation. l

                                                 n VISUAL 30. Movie:
                                                 Diversity of Life
                                                 The ultimate goal is
                                                 not just to find planets,
                                                 or even “hot Earths,”
                                                 but to find Earth-sized
                                                 planets that are not too
                                                 hot, and not too cold,
                                                 but just right for life to
                                                 develop.
                                                 If we do find Earth-sized
planets, it will be a tremendous discovery. Equally exciting is that the
Kepler mission is designed to settle the age old question of whether
planets like ours are common or not. Even if we do not find an Earth-
sized planet in the habitable zone of a star, that would also really
significant, because that would tell us that planets like ours are quite
rare, and our home planet all that much more precious and worth
preserving. And underlying everything, Kepler results have implications
in answering questions about the possibility of life existing elsewhere
in our galaxy. Are intelligent beings common or rare in the Universe?
Kepler mission is a serious first step to get real data that may eventually
lead to an answer that question!
                            VISUAL 31. Learn More. l
You can find out a lot more about this quest from the Kepler website,
kepler.nasa.gov. You can also join in the search at www.planethunters.
org.
Thank you for coming to our planetarium today!

                            VISUAL 32. Credits. l

                                                                                  27
Strange Planets
                                                                                                         PASS Classic

                                      About Exoplanets
California & Carnegie Planet Search                   PlanetQuest Website
    http://exoplanets.org/                                http://planetquest.jpl.nasa.gov/
The Extrasolar Planets Encyclopedia website at        Wikipedia, the free encyclopedia— “Extrasolar Planet” Wikimedia
   http://exoplanet.eu/                                  Foundation.
Kepler Mission website                                   http://en.wikipedia.org/wiki/Extrasolar_planets
   http://kepler.nasa.gov/                            Top 10 Most Intriguing Extrasolar Planets
Kepler Star Wheel:                                       http://www.space.com/scienceastronomy/extrasolar_planets.html
   http://kepler.nasa.gov/ed/starwheel/
Make a LEGO® Orrery:
  http://kepler.arc.nasa.gov/ed/sim/lego.html

                                        Worldwide Web Connections
                                       and updated information may be found at:
                                       http://www.lhs.berkeley.edu/pass

The Kepler team displays the variations in brightness in a graph of brightness versus time,
known as a light curve. One day, one of the Kepler scientists looked at the light curve of a
star identified in the Kepler Input Catalog (KIC) as KIC12253350 and thought that a section
of it looked like a heart. There was some moderate debate among some of the Kepler team
as to what kind of variable star KIC12253350 must be, but no conclusive categorization has
been agreed on. This T-shirt was produced for the January 2011 American Astronomical
Society meeting in Seattle and for Valentine’s Day 2011. Another Keper T-shirt has also
been made (Got Planets?)—see http://kepler.nasa.gov/education/fun/

                                       Black, back

                                                     White, back

                                             Black, front                                        White, front

28
Script

                                     Acknowledgments
  Production of Strange Planets was a joint effort of the     The following Lawrence Hall of Science staff ran the
Pacific Science Center planetarium (Alice Enevoldsen        pilot tests in summers of 2008and 2009: Simona Balan,
and Steve White) and the Lawrence Hall of Science           Malavika Lobo, Amelia Marshall, Margaret Nguyen,
Planetarium.                                                Katherine Koller, Alexandra Race, Sindhu Kubendran.
  Funding for Strange Planets was provided by two           Margaret Nguyen, Alexandra Race, and Sindhu Kuben-
sources:                                                    dran were actors for video sequences. Formative evaluation
                                                            concepts were devised and implemented by Lawrence Hall
• NASA Astrobiology Institute provided funds to Pacific     of Science Research, Evaluation, and Assessment (REA)
   Science Center for developing a version that was used    team member, Scott Randol as well as Dawn Robles of
   for schools in the state of Washington.                  Inverness Research Associates. Sallie Lin of REA served as
• NASA Kepler mission provided funds to Lawrence Hall       an observer for formative evaluation in the Lawrence Hall
   of Science to further develop the program and run        of Science pilot tests of 2008. Fiona Potter and Lucy Liu
   both local pilot tests in the LHS Holt Planetarium as    assisted in modeling the Walking Orrery that was added
   well as 70 planetariums nationwide. We are thankful      in 2011.
   to the Kepler Mission Principal Investigator, William       We are especially thankful to the following planetariums
   Borucki, and Deputy PI, David Koch for their solid       for field testing the show and providing feedback for the
   and consistent support for education and public out-     final version:
   reach projects.
                                                            Becky Lowder, Georgia Southern Planetarium,
   Thanks to Edna DeVore of SETI Institute for advice          Statesboro GA
and for arranging for the funding of free planetarium
show kits for the release of this program in the Interna-   Jack L. Northrup, Dr. Martin Luther King, Jr.
tional Year of Astronomy (2009).                                Planetarium at King Science and Technology Magnet
                                                                Omaha NE
                                                            Rod Martin, Brish Planetarium,
                                                               Hagerstown MD
                                                            Sheldon Shafer, Dave Grebner, Maegan Gilliland,
                                                               Lakeview Museum of Arts & Sciences,
                                                               Peoria IL

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Strange Planets   Strange Planets
                        PASS Classic

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